Spatial pattern of the threatened epiphytic bryophyte Neckera pennata at two scales in a fragmented boreal forest

The spatial pattern and occurrence of a threatened bryophyte, Neckera penna ta, were studied in relation to the abundance and pattern of suitable subst rate trees at two spatial scales: 1) in a 4 x 4 km fraction of fragmented, mostly managed southern boreal forest landscape, and 2) in an old-growth fo rest stand within this landscape, with abundant occurrence of suitable habi tats. To explore in detail the spatial clustering of N. pennata at the fore st stand scale, we applied a second order point process analysis based on t he Ripley's K-function for binary point patterns. Neckera a pennata proved to be a rare species in the studied landscape. it was found only on 31 Popu lus tremula trees. At the landscape scale, the distribution of the species was highly aggregated. the species occurred only within a 60 ha old-growth forest patch in the whole area. Ar the forest stand scale, N. pennata prove d to be a widespread, randomly distributed species without any tendency tow ards aggregation. It was found on 19 Populus trees, which was only 1.5% of the total 1253 potential substrate trees within the inventory area. The spe cies showed a statistically significant preference towards large trees. The future of the species in the study area is unclear due to 1) the very low population density and 2) the lack of regeneration of Populus within the pr otected old-growth forest area hosting the remaining population.